It's a tough choice. The apex isn't great with brittle paint as you said but you'll want brittle stuff since the apex gives you that added range. It depends how you play. Do you put several shots on one player or do you like to one ball / "snipe" people. If you're going to snipe you'll want the brittle stuff since you need to eliminate them in 1 shot, not bounce them and get their attention. I own an apex but use it only in the woods with cheap hard rec paint... Haven't tried anything brittle.

As far as Brittle, that only has to deal with your Bolt.
The barrel is not going to break brittle paint.
any paint will work.
Just think about how often you want your paint to break on target or bounce